/*
This code is from rfc1186. 
*/

/*
** ********************************************************************
** md4.c -- Implementation of MD4 Message Digest Algorithm           **
** Updated: 2/16/90 by Ronald L. Rivest                              **
** (C) 1990 RSA Data Security, Inc.                                  **
** ********************************************************************
*/

/*
** To use MD4:
**   -- Include md4.h in your program
**   -- Declare an MDstruct MD to hold the state of the digest
**          computation.
**   -- Initialize MD using MDbegin(&MD)
**   -- For each full block (64 bytes) X you wish to process, call
**          MDupdate(&MD,X,512)
**      (512 is the number of bits in a full block.)
**   -- For the last block (less than 64 bytes) you wish to process,
**          MDupdate(&MD,X,n)
**      where n is the number of bits in the partial block. A partial
**      block terminates the computation, so every MD computation
**      should terminate by processing a partial block, even if it
**      has n = 0.
**   -- The message digest is available in MD.buffer[0] ...
**      MD.buffer[3].  (Least-significant byte of each word
**      should be output first.)
**   -- You can print out the digest using MDprint(&MD)
*/

/* Implementation notes:
** This implementation assumes that ints are 32-bit quantities.
** If the machine stores the least-significant byte of an int in the
** least-addressed byte (e.g., VAX and 8086), then LOWBYTEFIRST
** should be set to TRUE.  Otherwise (e.g., SUNS), LOWBYTEFIRST
** should be set to FALSE.  Note that on machines with LOWBYTEFIRST
** FALSE the routine MDupdate modifies has a side-effect on its input
** array (the order of bytes in each word are reversed).  If this is
** undesired a call to MDreverse(X) can reverse the bytes of X back
** into order after each call to MDupdate.
*/
#define LOWBYTEFIRST

/* Compile-time includes
*/

#include "lib.h"
#include "md4.h"

/* Compile-time declarations of MD4 "magic constants".
*/
#define I0  0x67452301       /* Initial values for MD buffer */
#define I1  0xefcdab89
#define I2  0x98badcfe
#define I3  0x10325476
#define C2  013240474631     /* round 2 constant = sqrt(2) in octal */
#define C3  015666365641     /* round 3 constant = sqrt(3) in octal */
/* C2 and C3 are from Knuth, The Art of Programming, Volume 2
** (Seminumerical Algorithms), Second Edition (1981), Addison-Wesley.
** Table 2, page 660.
*/

#define fs1  3               /* round 1 shift amounts */
#define fs2  7
#define fs3 11
#define fs4 19
#define gs1  3               /* round 2 shift amounts */
#define gs2  5
#define gs3  9
#define gs4 13
#define hs1  3               /* round 3 shift amounts */
#define hs2  9
#define hs3 11
#define hs4 15

/* Compile-time macro declarations for MD4.
** Note: The "rot" operator uses the variable "tmp".
** It assumes tmp is declared as unsigned int, so that the >>
** operator will shift in zeros rather than extending the sign bit.
*/
#define f(X,Y,Z)             ((X&Y) | ((~X)&Z))
#define g(X,Y,Z)             ((X&Y) | (X&Z) | (Y&Z))
#define h(X,Y,Z)             (X^Y^Z)
#define rot(X,S)             (tmp=X,(tmp<<S) | (tmp>>(32-S)))
#define ff(A,B,C,D,i,s)      A = rot((A + f(B,C,D) + X[i]),s)
#define gg(A,B,C,D,i,s)      A = rot((A + g(B,C,D) + X[i] + C2),s)
#define hh(A,B,C,D,i,s)      A = rot((A + h(B,C,D) + X[i] + C3),s)

/* MDbegin(MDp)
** Initialize message digest buffer MDp.
** This is a user-callable routine.
*/
void
MDbegin(MDptr MDp)
{
	int i;
	MDp->buffer[0] = I0;
	MDp->buffer[1] = I1;
	MDp->buffer[2] = I2;
	MDp->buffer[3] = I3;
	for (i=0;i<8;i++)
		MDp->count[i] = 0;
	MDp->done = 0;
}

#if 0

/* MDreverse(X)
** Reverse the byte-ordering of every int in X.
** Assumes X is an array of 16 ints.
** The macro revx reverses the byte-ordering of the next word of X.
*/
#define revx { t = (*X << 16) | (*X >> 16); \
  *X++ = ((t & 0xFF00FF00) >> 8) | ((t & 0x00FF00FF) << 8); }
static void  
MDreverse(uint32 *X)
{
	register uint32 t;
	revx; revx; revx; revx; revx; revx; revx; revx;
	revx; revx; revx; revx; revx; revx; revx; revx;
}

#endif


/* MDblock(MDp,X)
** Update message digest buffer MDp->buffer using 16-word data block X.
** Assumes all 16 words of X are full of data.
** Does not update MDp->count.
** This routine is not user-callable.
*/
static void
MDblock(MDptr MDp, uint32 *X)
{
	register uint32 tmp, A, B, C, D;
#ifndef LOWBYTEFIRST
	MDreverse(X);
#endif
	A = MDp->buffer[0];
	B = MDp->buffer[1];
	C = MDp->buffer[2];
	D = MDp->buffer[3];
	/* Update the message digest buffer */
	ff(A , B , C , D ,  0 , fs1); /* Round 1 */
	ff(D , A , B , C ,  1 , fs2);
	ff(C , D , A , B ,  2 , fs3);
	ff(B , C , D , A ,  3 , fs4);
	ff(A , B , C , D ,  4 , fs1);
	ff(D , A , B , C ,  5 , fs2);
	ff(C , D , A , B ,  6 , fs3);
	ff(B , C , D , A ,  7 , fs4);
	ff(A , B , C , D ,  8 , fs1);
	ff(D , A , B , C ,  9 , fs2);
	ff(C , D , A , B , 10 , fs3);
	ff(B , C , D , A , 11 , fs4);
	ff(A , B , C , D , 12 , fs1);
	ff(D , A , B , C , 13 , fs2);
	ff(C , D , A , B , 14 , fs3);
	ff(B , C , D , A , 15 , fs4);
	gg(A , B , C , D ,  0 , gs1); /* Round 2 */
	gg(D , A , B , C ,  4 , gs2);
	gg(C , D , A , B ,  8 , gs3);
	gg(B , C , D , A , 12 , gs4);
	gg(A , B , C , D ,  1 , gs1);
	gg(D , A , B , C ,  5 , gs2);
	gg(C , D , A , B ,  9 , gs3);
	gg(B , C , D , A , 13 , gs4);
	gg(A , B , C , D ,  2 , gs1);
	gg(D , A , B , C ,  6 , gs2);
	gg(C , D , A , B , 10 , gs3);
	gg(B , C , D , A , 14 , gs4);
	gg(A , B , C , D ,  3 , gs1);
	gg(D , A , B , C ,  7 , gs2);
	gg(C , D , A , B , 11 , gs3);
	gg(B , C , D , A , 15 , gs4);
	hh(A , B , C , D ,  0 , hs1); /* Round 3 */
	hh(D , A , B , C ,  8 , hs2);
	hh(C , D , A , B ,  4 , hs3);
	hh(B , C , D , A , 12 , hs4);
	hh(A , B , C , D ,  2 , hs1);
	hh(D , A , B , C , 10 , hs2);
	hh(C , D , A , B ,  6 , hs3);
	hh(B , C , D , A , 14 , hs4);
	hh(A , B , C , D ,  1 , hs1);
	hh(D , A , B , C ,  9 , hs2);
	hh(C , D , A , B ,  5 , hs3);
	hh(B , C , D , A , 13 , hs4);
	hh(A , B , C , D ,  3 , hs1);
	hh(D , A , B , C , 11 , hs2);
	hh(C , D , A , B ,  7 , hs3);
	hh(B , C , D , A , 15 , hs4);
	MDp->buffer[0] += A;
	MDp->buffer[1] += B;
	MDp->buffer[2] += C;
	MDp->buffer[3] += D;
}

/* MDupdate(MDp,X,count)
** Input: MDp -- an MDptr
**        X -- a pointer to an array of unsigned characters.
**        count -- the number of bits of X to use.
**          (if not a multiple of 8, uses high bits of last byte.)
** Update MDp using the number of bits of X given by count.
** This is the basic input routine for an MD4 user.
** The routine completes the MD computation when count < 512, so
** every MD computation should end with one call to MDupdate with a
** count less than 512.  A call with count 0 will be ignored if the
** MD has already been terminated (done != 0), so an extra call with
** count 0 can be given as a "courtesy close" to force termination
** if desired.
*/
void
MDupdate(MDptr MDp, uint8 *X, uint32 count)
{
	uint32 i, tmp, bit, byte, mask;
	uint8 XX[64];
	uint8 *p;
	/* return with no error if this is a courtesy close with count
	** zero and MDp->done is true.
	*/
	if (count == 0 && MDp->done)
		return;
	/* check to see if MD is already done and report error */
	if (MDp->done)
	{ DEBUGMSG(("\nError: MDupdate MD already done.")); return; }
	/* Add count to MDp->count */
	tmp = count;
	p = MDp->count;
	while (tmp)
	{
		tmp += *p;
		*p++ = (uint8)(tmp & 0xFF);
		tmp = tmp >> 8;
	}
	/* Process data */
	if (count == 512)
	{ /* Full block of data to handle */
		MDblock(MDp,(uint32 *)X);
	}
	else if (count > 512) /* Check for count too large */
	{
		DEBUGMSG(("\nError: MDupdate called with illegal count value %d.", count));
		return;
	}
	else /* partial block -- must be last block so finish up */
	{ /* Find out how many bytes and residual bits there are */
		byte = count >> 3;
		bit =  count & 7;
		/* Copy X into XX since we need to modify it */
		for (i=0;i<=byte;i++)
			XX[i] = X[i];
		for (i=byte+1;i<64;i++)
			XX[i] = 0;
		/* Add padding '1' bit and low-order zeros in last byte */
		mask = 1 << (7 - bit);
		XX[byte] = (uint8)((XX[byte] | mask) & ~( mask - 1));
		/* If room for bit count, finish up with this block */
		if (byte <= 55)
		{
			for (i=0;i<8;i++)
				XX[56+i] = MDp->count[i];
			MDblock(MDp,(uint32 *)XX);
		}
		else /* need to do two blocks to finish up */
		{
			MDblock(MDp,(uint32 *)XX);
			for (i=0;i<56;i++)
				XX[i] = 0;
			for (i=0;i<8;i++)
				XX[56+i] = MDp->count[i];
			MDblock(MDp,(uint32 *)XX);
		}
		/* Set flag saying we're done with MD computation */
		MDp->done = 1;
	}
}

/*
** End of md4.c
*/
